The present application relates to a micro-resonator, a band-pass filter using the micro-resonator, a semiconductor device including the micro-resonator, and a communication apparatus using a band-pass filter including the micro-resonator.
Wireless communication technology has greatly advanced in recent years, and there has been a demand for size and weight reduction in a communication apparatus using the wireless communication technology. Micro electro mechanical system (MEMS) technology to manufacture a micro mechanical structure by using micro-processing technology used for a semiconductor has been used in an RF (high frequency) signal processing portion where size reduction has been a longstanding issue. For example, there is a mechanical filter using mechanical resonance, which is small in size and is capable of being integrated, and so it is expected to be applied to a communication field. Use of such a MEMS element as an RF filter has been proposed by research institutes including Michigan University (see, C. T-Nguyen, Micromechanical components for miniaturized low-power communications (invited plenary), proceedings, 1999 IEEE MTT-S International Microwave Symposium RF MEMS Workshop, Jun. 18, 1999, pp. 48-77).
A resonance characteristic of a resonator in a mechanical filter has an asymmetrical form having a resonance peak and an anti-resonance peak. When such resonance characteristics are combined to manufacture a band-pass filter, a plurality of resonators each having a different resonance frequency or a peripheral circuit to change the phase of a signal are needed. Because of the above, the whole area becomes large and a small-sized filter may not be obtained. When a higher harmonic wave is used, two signals of opposite phases can be obtained in one resonator, however, respective frequencies may not be adjusted independently in that case.